1. Field of the Invention
This invention is related to dentures and to an apparatus and method for locating lost dentures. This invention is also related to a signaling device that can be mounted in existing dentures or incorporated in new dentures and to a detector for locating the signaling device, attached to the lost denture within a certain area or an interrogation zone. The detector area or interrogation zone could be located at a building exit leading to a trash disposal collection area. This device is also related to devices for transmitting an electromagnetic field and detectors for locating a signal generated in response to the electromagnetic field.
2. Description of the Prior Art
Medical institutions and long term care facilities in which patients and residents may suffer from diminished mental capacity or simple forgetfulness frequently have difficulty locating personal articles that have been misplaced or lost. One problem that is often encountered is that the patients or residents tend to lose or misplace their dentures. Patients or residents in such facilities often inadvertently throw their dentures in trash receptacles, leave them in pockets of clothing that is taken to a laundry facility or leave then on serving trays after meals. In rest homes and nursing care facilities, the resident may also place the dentures under sheets, in closets or in drawers where they can be difficult to locate. In some cases, the dentures are subsequently located by the institution""s personnel, who cannot identify the owner. In other situations the lost dentures are inadvertently disposed of in the trash or simply cannot be found within a reasonable time.
Although this problem occurs even when the institutions personnel are vigilant, it is especially upsetting to the residents and to their relatives. Lost dentures can be costly to replace, and relatives can be especially upset that the institution cannot keep track of their older relative""s dentures. In many cases, the institution must replace the dentures and is not reimbursed.
Medical institutions do encounter problems with lost articles in other contexts. For example, U.S. Pat. No. 5,923,001 discloses a surgical sponge detection system for use in an operating room in which detectable RF tags are attached to the sponges. U.S. Pat. No. 5,664,582 discloses a marker that can be used on a surgical instrument. However, these devices are used only within a controlled environment, and the problem of lost dentures arises because it is not possible to control the environment in which the loss may occur.
U.S. Pat. No. 4,160,971 discloses a passive transponder without a local power supply that is remotely powered by received transmissions. This device is primarily intended to measure pressure on dental plates. However, this device is intended to provide telemetry instead of a locator signal and it does not appear to be adapted for incorporation into denture that would be used for an extended period of time by an ordinary denture wearer. It also does not to be adapted for use with an existing denture.
Implants for use in a prosthesis are shown in U.S. Pat. No. 5,300,609 and in U.S. Pat. No. 5,855,909. However, these devices are also intended for data transmission instead of as a locator, and as such would not have the range to locate lost dentures.
In accordance with this invention, a dental insert for use in locating a lost artificial denture includes an internal signaling component. The signaling component emits a signal in response to an external electromagnetic field and is embedded in an exterior layer transparent to the external electromagnetic field. The exterior layer is bondable to the denture on at least one side and is suitable for introduction into the oral cavity of a denture wearer without causing irritation to the denture wearer""s mouth while at the same time isolating the internal signaling component from the oral cavity and any fluids that might damage the signaling component if subjected to prolonged exposure. In one embodiment, and exterior side of the insert is shaped to conform to the local surface of the denture after the denture has been mounted in a recess in the denture.
A transmitter-detector unit is also employed. An electromagnetic field is transmitted and if the denture is within an interrogation zone, the internal signaling component emits a signal that can be detected by the detector unit. The transmitter-detector can be portable or stationary, and the transmitter and detector can either be in the same unit or in different units.
In a maxillary or upper denture, the signaling device or button can be mounted in the palatal vault area. The thickness of the device should be small so as not to cause irritation to the tongue or to the palate. Preferable the thickness of the signaling button or locator strip should be less than the local thickness of the palatal vault to which the locating button will conform. The signaling device or button may also be located on the interior lingual surface of a maxillary denture, just below the teeth. In the mandibular or lower denture, the locator button can be located on the lingual surface of the denture flange. The signaling device can also be located in a cavity formed in the molar area of either the upper or lower denture.
A resin layer surrounds the internal signaling component. This layer both isolates the signaling device from the denture wearer""s mouth or oral cavity and provides a means for bonding the button to the denture.
In a preferred embodiment, the button also includes a visible external indicia or marking that can be used to identify the denture""s owner. This visible external indicia could be a serial number, the owner""s name or a unique bar code. This information could be stored on an accessible computer data base to permit the health care institution, or any other entity having access to the database, to determine the owner of the lost denture as well as any additional information stored in the database.
Passive locator strips suitable for use in the preferred embodiment of this invention can be o the types shown in the following patents or in devices having similar or equivalent characteristics.
U.S. Pat. No. 3,747,086xe2x80x94Deactivatable Ferromagnetic Marker for Detection of Objects Having Marker Secured Thereto and Method and System of Using Same
U.S. Pat. No. 4,510,489xe2x80x94Surveillance System Having Magnetomechanical Marker
U.S. Pat. No. 4,660,025xe2x80x94Article Surveillance Magnetic Marker Having an Hysteresis Loop with Large Barkhausen Discontinuities
U.S. Pat. No. 5,029,291xe2x80x94Electromagnetic Sensor Element and Methods and Apparatus for Making and Using Same
Numerous other patents show similar magnetic sensor elements that respond to an variable external electromagnetic field.